Thammacharoen Sumpun, Semsirmboon Sapon, Chanpongsang Somchai, Chaiyabutr Narongsak, Panyasomboonying Pawares, Khundamrongkul Paweenut, Puchongmart Peeravit, Wichachai Worapruch
Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand.
Department of Animal Husbandry, Faculty of Veterinary Science, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand.
Vet World. 2021 Sep;14(9):2392-2396. doi: 10.14202/vetworld.2021.2392-2396. Epub 2021 Sep 16.
Metabolism and environment are closely related. Under high ambient temperature (HTa), dairy cows may have different energy metabolism during summer and winter. The present study was carried out to investigate the effect of HTa on the milk yield and blood concentration of beta-hydroxybutyrate (BHBA) and glucose at the herd level.
One large dairy farm in Thailand with more than 100 crossbred Holstein cows milked each month was selected. The first experiment was performed on non-lactating cows to determine the normal daily concentrations of blood BHBA and glucose. Under the HTa condition, there was no significant change in blood BHBA and glucose concentrations. The second experiment was performed using a prospective cohort clinical design to demonstrate the seasonal effect on milk yield and blood BHBA as an indication of energy metabolism at the herd level.
The temperature and humidity index for the winter (78.1±0.5) and summer (83.4±0.7) periods differ significantly. The average milk yield during the winter period was 17.8% higher than during the summer period. The reduction of body condition score (BCS) during early lactation was significant in the winter cows. Both higher milk yield and lower BCS in the winter cows suggested a state of negative energy balance. However, there was no difference in blood BHBA and glucose concentrations between winter and summer cows. The effect of HTa on insulin signaling appeared to be a counterbalancing factor for the ketogenic status. Based on the present results, it would be interesting to further investigate the incidence of subclinical and clinical ketosis in a dairy farm under tropical conditions.
The present experiment revealed that HTa during summer decreased milk yield in dairy cows fed under tropical conditions. Higher milk yield in winter caused a greater reduction of BCS and suggested a greater negative energy balance. However, there was no seasonal effect on blood BHBA and glucose concentrations.
代谢与环境密切相关。在高环境温度（HTa）下，奶牛在夏季和冬季可能具有不同的能量代谢。本研究旨在探讨HTa对牛群水平的产奶量以及β-羟基丁酸（BHBA）和葡萄糖血液浓度的影响。
选择泰国一个大型奶牛场，每月挤奶的杂交荷斯坦奶牛超过100头。第一个实验在非泌乳奶牛上进行，以确定血液中BHBA和葡萄糖的正常日浓度。在HTa条件下，血液中BHBA和葡萄糖浓度没有显著变化。第二个实验采用前瞻性队列临床设计，以证明季节对产奶量和血液BHBA的影响，作为牛群水平能量代谢的指标。
冬季（78.1±0.5）和夏季（83.4±0.7）的温度湿度指数有显著差异。冬季的平均产奶量比夏季高17.8%。冬季奶牛在泌乳早期体况评分（BCS）的降低显著。冬季奶牛较高的产奶量和较低的BCS均表明处于负能量平衡状态。然而，冬季和夏季奶牛的血液BHBA和葡萄糖浓度没有差异。HTa对胰岛素信号的影响似乎是生酮状态的一个平衡因素。基于目前的结果，进一步研究热带条件下奶牛场亚临床和临床酮病的发生率将很有意思。
本实验表明，夏季的HTa降低了热带条件下饲养的奶牛的产奶量。冬季较高的产奶量导致BCS更大程度的降低，并表明负能量平衡更大。然而，血液中BHBA和葡萄糖浓度没有季节性影响。
